Switch position indicator for electromagnetic switchgear

ABSTRACT

An improved indicating device for use with electromagnetic switchgear, particularly such switchgear having a detachable arcing chamber, in which a two piece indicator is moved by the movable contact in the switchgear to provide an external indication of the switchgear position. The two pieces of the indicating device are connected through a threaded connection so that they can be adjusted to compensate for tolerances in the manufacturer of the arcing chamber.

United States Patent 11 1 [11] 3,873,797 Hannich Mar. 25, 1975 1 1 SWITCH POSITION INDICATOR FOR 2,441,137 5/1948 De Anthony 200/308 ELECTROMAGNETIC SWITCHGEAR 2,625,625 1/1953 lngwersen 200/308 [75] lnventor: Joachim Hannich, Amberg, FORElGN TE TS OR PPLICATIONS Germany 97.615 8/1924 Austria 200/308 [73] Assignee: Siemens Aktlengesellschaft, Munich, I

Germany Primary ExammerRobert S. Macon Attorney, Agent, or Firm--Keny0n & Kenyon Reilly [22] Flled: Aug. 7, 1973 c & Chapin [21] Appl. No.: 386,437

[57] ABSTRACT [30] Foreign Application Priority Data An improved indicating device for use with electro- Aug' 14 1972 Germany 7230068 magnetic switchgear, particularly such switchgear having a detachable arcing chamber, in which a two piece 52 us. c1. 200/308, 200/144 R indicator is moved by the movable contact in the [51] Int. Cl. ..H01h 9/16 Switchgear to Provide external indication of the [58] Field of Search 200/308 144 R Switchgear positihh- The two Pieces of the indicating device are connected through a threaded connection [56] References Cited so that they can be adjusted to compensate for toler- UNITED STATES PATENTS ances in the manufacturer of the arcing chamber. 457.483 8/1891 Silvey 200/308 8 main, 2 Drawing Figures SWITCH'POSITION INDICATOR FOR ELECTROMAGNETIC SWITCHGEAR BACKGROUND OF THE INVENTION This invention relates to electromagnetic switchgear in general and more particularly to an improved switch position indicator for such switchgear.

In the type of switchgear designed with a nondetachable arcing chamber it is common practice to have an extension of the contact bridge carrier protrude beyond the contour of the switch housing when the switch is in the open position. When the switch is closed, the extension disappears into the switch housing so that an observer can conclude that the switch is closed. On the other hand, switchgear having a detachable arcing chamber has in general been constructed so that the switching magnets next to the arcing chamber are visible so that it is possible to deduce the position of the switch from the position of the actuator magnet. Such an indication is not always accurate since a break of the connection between the switching magnet and the switch contact themselves can lead to a false indication of position. Thus it is more desirable that the switch position indication be dependent on the movable contact themselves in the manner in which such indications are provided in non-detachable arcing chambers as described above. In German design Patent No. 71 165 59.8 an indicating member loaded by a return spring is guided in the arcing chamber and movable in the closing direction of the movable contact with limited mobility. This indicating member is pushed above the contour of the arcing chamber by the movable part of the switch when the contact are open. In the design shown therein the indicating member is held in the arcing chamber by a sheet metal part preferably designed as a are baffle with the sheet metal part riveted to the arcing chamber. Since the arcing chamber has a relatively large manufacturing tolerance as compared to the switching apparatus itself, the part protruding above the contour of the arcing chamber is not the same for all switches with the result that an accurate indication of switchgear position is not always possible. Thus there is a need for an improved type switch position indicator which is responsive to motion of the switching contacts themselves and which will accurately provide an indication despite any manufacturing tolerances encountered in the arcing chamber.

SUMMARY OF THE INVENTION The switch position indicator of the present invention provides such an indication. It is usable in both switchgear having a fixed arcing chamber and that with a detachable arcing chamber, providing a reliable indication of switchgear position in each case. To accomplish this the indicator is made of two parts which are adjustable relative to each other, with the indicator loaded by a return spring and guided so as to be movable with limited mobility as the contacts of the switch move. The indicator is moved by the moving contacts of the switch so as to extend above the contour of the arcing chamber to provide an indication of an open position and with the closing of the contacts retracts into the housing so that it is no longer visible, indicating a closed position. By making the indicator in two parts that are adjustable with respect to each other, the tolerances in the arcing chamber can be compensated for so that the indicator will give a reliable indication in each installation. As opposed to some prior art devices, assembly is simplified in that it is not necessary to fish any extensions which are in connection with the contact bridge carrier through openings in the arcing chamber. In the illustrated embodiment the adjustment between the two parts is done by internally threading one part. and externally threading the other so that they may be screwed in and out with respect to each other to shorten and lengthen the overall length of the indicating device. Other means of adjustment are also possible such as providing locking action between the two parts, using detents or by cementing once proper adjustment is made. To prevent any gases leaking out of the arcing chamber the projecting or protruding portion of the indicator is made with an annular extension which fits into a matching recess on the top of the arcing chamber to thereby form an effective labyrinth seal. By designing the part holding the spring as a spring retainer which partially engages over the spring, damage to the spring by arcs within the arcing chamber is also avoided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of magnetic switchgear having the indicator of the present invention installed.

FIG. 2 is an elevation view, also in cross-section of the embodiment of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT As shown on FIGS. 1 and 2, the switchgear is supported by a base onto which are mounted two fixed contacts 3 secured in place by means of bolts 2. Also connected to the base 1 is an arcing chamber 4 having installed therein quenching baffles 5 and an arc guiding bridge 6. When operated, the two fixed contacts 3 are bridged by a movable contact bridge 7. The contact bridge is connected through a leaf spring 8, over which is placed a yoke 9 connected to a helical spring 10, to a plastic part 11 which is in turn mounted on movable switching magnets. The arrangement ofthe yoke 9 may more clearly be seen from an examination of FIG. 2. What has been described so far is a conventional switchgear arrangement.

The indicator 12 of the present invention comprises the two parts 14 and 15 which are adjustable relative to each other. Part 14 is on top in operation will protrude above the contour of the arcing chamber 4 when the switch is opened. Part 15 connected thereto serves as the spring retainer for a spring 13 which will tend to pull the indicator 12 into the position where it does not protrude above the arcing chamber. In the position shown, the switch is in the opened position and the yoke 9 is pushing against the base of the part 15 thereby compressing the spring and pushing the indicator 12 up so that the part 14 is above the contour of the arcing chamber 4. When the switch is closed and the bridging member 7 andall its associated parts including the yoke 9 lowered, the force of the spring 13 will cause the device 12 to be brought down below the contour of the arcing chamber 4. The spring 13 acts between the member 15 and the inside wall of the arc guide 6 as shown. The top part 14 has an annular extension 18 which tits into a matching annular recess 19 formed in the top of the arcing chamber 14 to thereby form a labyrinth seal to prevent gases within the arcing chamber escaping therefrom. Preferably the top portion 14 along with its annular protrusion and the annular recess 19 will be made of a square shape to prevent the turning of the upper portion 14 relative to the lower portion 15 and the arcing chamber. The parts 14 and 15 are connectd with a threaded connection. The part 14 contains an internal recess 16 which has internal threads cut therein. The part 15 has a threaded extension 17 which screws into the internal threads in the recessed 16. The threads can be made with slightly different pitch so as to provide a tighter connection. The lower part 15 contains a'hexagonal recess 20 in its bottom so that an Allen wrench may be inserted therein to adjust the relative length of the overall indicating device 12. This length will be adjusted in each individual switchgear to compensate for manufacturing tolerance in the arcing chamber 4 such that in the opened position a visible protrusion of the indicator 12 above the arcing chamber will result but so that the length is not so long thatpressing down upon the indicator 12 will close the switch.

The bottom part 15 is made as a disk which is larger than needed to retain spring 13 in order to prevent any are which might be drawn between spring 8 and bridge 6 from hitting the spring 13. Further protection may be obtained by extending the disk to form an annular recess in which the spring 13 is enclosed as shown by the dotted lines on FIG. 1.

Thus an improved switch indicator which is usable in switchgear having removable arcing chambers made to low manufacturing tolerances has been shown. Although a specific embodiment has been illustrated and described it will be obvious to those skilled in the art that various modifications may be made without departing from the spirit of the invention which is intended to be limited solely by the appended claims.

What is claimed is:

1. A switch position indicator for an electromagnetic switchgear of the type which has a detachable arcing chamber comprising:

a. an indicating member guided in a suitable recess in the arcing chamber for limited motion in the direction of movement of the movable contact in the switchgear;

b. a spring acting upon said indicating member so as to tend to force it in the closing direction of the movable contacts, and

c. wherein said indicating member is comprised of:

l. a first bottom part mechanically coupled with the movable contact of the switch;

2. a second upper part which has at least a portion capable of protruding above the acring chamber; and

3. means for adjustably coupling said two parts such that the overall length of the indicating member may be adjusted.

2. The invention according to claim 1 wherein said means to couple comprises threaded means.

3. The invention according to claim 2 wherein said means to couple comprises a recess in said second upper part which is threaded containing internal threads and a threaded extention on said first lower portion having external threads which are screwed into the internal threads of said upper part.

4. The invention according to claim 3 wherein said internal and external threads have a different pitch.

5. The invention according to claim 1 wherein said second upper part of said indicating member contains an annular extension projecting downwardly and wherein said arcing chamber has a matching annular recess to thereby form a labyrinth seal when the switchgear is closed.

6. The invention according to claim 1 wherein said first lower part contains a means for holding said spring, which part partially is arranged for protecting it from arcs within the chamber.

7. The invention according to claim 6 wherein said means for holding comprises an enlarged disk on the bottom of said lower part.

8. The invention according to claim 7 and further including sides extending up from the edges of said disk to form an annular recess which engages over said spring. 

1. A switch position indicator for an electromagnetic switchgear of the type which has a detachable arcing chamber comprising: a. an indicating member guided in a suitable recess in the arcing chamber for limited motion in the direction of movement of the movable contact in the switchgear; b. a spring acting upon said indicating member so as to tend to force it in the closing direction of the movable contacts, and c. wherein said indicating member is comprised of:
 1. a first bottom part mechanically coupled with the movable contact of the switch;
 2. a second upper part which has at least a portion capable of protruding above the acring chamber; and
 3. means for adjustably coupling said two parts such that the overall length of the indicating member may be adjusted.
 2. a second upper part which has at least a portion capable of protruding above the acring chamber; and
 2. The invention according to claim 1 wherein said means to couple comprises threaded means.
 3. The invention according to claim 2 wherein said means to couple comprises a recess in said second upper part which is threaded containing internal threads and a threaded extention on said first lower portion having external threads which are screwed into the internal threads of said upper part.
 3. means for adjustably coupling said two parts such that the overall length of the indicating member may be adjusted.
 4. The invention according to claim 3 wherein said internal and external threads have a different pitch.
 5. The invention according to claim 1 wherein said second upper part of said indicating member contains an annular extension projecting downwardly and wherein said arcing chamber has a matching annular recess to thereby form a labyrinth seal when the switchgear is closed.
 6. The invention according to claim 1 wherein said first lower part contains a means for holding said spring, which part partially is arranged for protecting it from arcs within the chamber.
 7. The invention according to claim 6 wherein said means for holding comprises an enlarged disk on the bottom of said lower part.
 8. The invention according to claim 7 and further including sides extending up from the edges of said disk to form an annular recess which engages over said spring. 